This research is focused on the development of new techniques, based on the hydrophobicity of their surfaces, for separating, characterizing, and manipulating proteins. (The proposal is an extensively revised version of a previous proposal that was not funded.) Improving the methods used to separate, characterize, and manipulate proteins is broadly important in biochemistry and molecular biology: areas of application include proteomics and systems biology, purification of protein therapeutics, use in lab-on-a-chip analytical systems for clinical analyses, rational drug design, and fundamental protein science. The proposed research has five specific objectives: 1. To develop a new, validated model system for studying the biophysics of hydrophobic regions of protein surfaces. 2. To develop new techniques for characterization of proteins based on their susceptibility to denaturation by hydrophobic surfactants and hydrotropes (e.g., SDS, not urea). 3. To rationalize systems that use hydrophobic surfactants in manipulating proteins. 4. To provide a solution to the problem of adsorption of proteins on the hydrophobic walls of microchannels in plastic LoC systems. 5. To help to understand the influence of hydrophobicity and organic character of the medium on binding of ligands to proteins. Lay Description: This research will contribute to the analysis and purification of proteins used in treatment of human disease, and to the development of instrumental techniques useful in the diagnosis of disease, in screening for public health, and in response to biological events (emerging disease, bioterrorism).